The present invention relates generally to radiation detectors employing scintillation or wave length shifting optical fiber arrays arranged in a two-dimensional X-Y plane for providing signals indicative of the locations of nuclear reactions occurring in the X-Y plane. More particularly, the present invention is directed to such radiation detectors wherein the optical fiber arrays are each provided by a plurality of side-by-side optical fibers with these optical fiber arrays disposed perpendicular to one another and in the X-Y plane and with a planar layer of nuclear reactive material operatively associated with the optical fiber arrays. Each nuclear particle or ray that contacts and reacts with the layer of nuclear reactive material will simultaneously provide a light pulse in a single optical fiber in each optical fiber array with these light pulses together being used to determine the X-Y coordinates of each nuclear reaction with a resolution of less than one millimeter (mm).
Position sensitive radiation detectors are of significant interest in many experimental and production applications. For example, the determination of essentially the precise location of neutron activity in research facilities, including those employing cold and thermal neutron scattering experiments, is often of considerable importance in achieving the goal of the research. Also, in production facilities involving nuclear activity such as in the production of tritium in a nuclear reactor, the dimensional profiles of the reactor target materials are important considerations in the operation of the reactor and the production of the tritium. Further, an accurate determination of fission density distribution in a nuclear reactor is a significant criterion in the design and operation of the reactor. Also, with the storage of fissile material in storage vaults, the imaging of the fissile material stored in each location in the vault would provide a valuable monitoring mechanism.
Various types of position sensitive neutron detectors have been recently developed and are described in the literature such as in the article, "Experience With Position-Sensitive Neutron Detectors at the Intense Pulsed Neutron Source", R. K. Crawford et al, Nuclear Instruments and Methods in Physics Research, A299 (1990) pp. 17-24. The position sensitive neutron detectors described in this article include detectors employing .sup.6 Li-glass scintillators in connection with multiple channel photomultiplier arrays and .sup.3 He proportional counters for providing two-dimensional (X-Y) coordinates of neutron activity with spatial resolutions in the range of about 0.7 to 14.0 mm.